The present invention relates generally to containers made of paperboard or other semi-rigid materials, especially liquid-tight aseptic containers, and relates more particularly to containers of that type having a brick-shaped configuration.
The constructions of various parallelepipedic and other non-round containers are known in the art. Examples are disclosed in U.S. Pat. Nos. 2,232,088 and 2,374,793, issued to H. F. Waters, as well as U.S. Pat. No. 3,067,923, issued to C. W. Thiets, and U.S. Pat. No. 3,390,829, issued to H. S. Malby. Typically, such containers are formed from blanks or laminate sheets provided with a pattern of score lines or fold lines along which the blank is folded to form a container which includes a bottom end wall and a triangular flap, or dog ear, projecting most commonly from each of the shorter sides of the bottom end wall. The dog ears consist of excess material not needed to define the six faces or walls of the body of the container and are typically folded in against the bottom end wall.
The folding in of the dog ears presents problems as to flatness and stability of the container bottom, particularly in those cases where both the bottom end wall and each dog ear contain sealing fins (tabs or flaps formed during construction of the container by sealing the edge portions of two layers of material together face to face). In such instances, a relatively large number of layers of laminate material (e.g., as many as eight) are located on top of each other where the dog ears are folded against the bottom end wall, resulting in an excess of folded material at the bottom of the container. Because of this excess material, the bottom of the container is no longer flat, and the ability of the container to stand upright in a stable manner is reduced.
Two recent patents disclose attempts to solve this problem. U.S. Pat. No. 3,998,378, issued to W. Vetten, describes a box with a rectangular bottom that is said to arch inward at its center due to the procedure disclosed in that patent for constructing the container from a blank. The part of the blank that will become the bottom portion of the container consists of two sets of panels. The panels of one set, which will form dog ears upon folding, are located most commonly at shorter sides of the box and those of the other set are rectangular areas which will form the end wall panels of the container bottom. During container construction, the dog ears are first folded inward and are then overlapped by the rectangular end wall panels to form the bottm of the container. The bottom is then sealed via a fillet seam along the periphery of the bottom end wall.
U.S. Pat. No. 4,267,957, issued to Holmstrom, discloses a differently shaped package bottom. No crease lines are provided for the dog ears to be folded at. Instead, crease lines are provided on the bottom end wall panel, each with one end at a corner where the dog ear joins the bottom end wall, the other end of each slanting slightly toward the center of the bottom end wall. This scoring pattern results in an inward bending of the sides of the bottom end wall along the crease line when the dog ears are folded in against the bottom end wall, thus eliminating bulging of the container in those areas.
In contrast, the present invention utilizes novel sealing or creasing patterns on a sheet of semi-rigid container material which, upon construction of the container, result in an inward bending of the central portion of the bottom end wall. A space is thereby created into which the dog ears can be neatly placed, resulting in a flatter, more stable container bottom.
It is therefore the principal object of the present invention to provide a liquid-tight aseptic container made of paperboard or a similar semi-rigid material, and having a bottom of improved flatness and stability.
Another object of the invention is to provide a blank of semi-rigid material scored appropriately for folding to form such a container with an improved bottom.
Still another object of the invention is to provide a laminate web of semi-rigid material having a plurality of prescored regions to be utilized in the production of containers with bottoms of improved flatness and stability.